It is known that fish are attracted by some sounds. A well-known animated film showed fish enticed by and swimming around an underwater speaker playing a waltz. Live insects create noises which are audible to fish, frequently resulting in a fish's almost immediate "striking" the insect. An example of the latter is the cicada or locust which produces a loud shrill sound which fish find irrestible.
Many sonic lures have been proposed to attract fish. Typically, these have been battery operated buzzers or trolling lures which have low resonant frequencies that emit sound when excited by the relative motion of the lure through the water.
The present invention differs from any of the prior sonic fishing lures. Rather than emitting a single characteristic sound at all velocities, this invention produces musical notes whose frequency is a controllable variable, being directly proportional to the relative velocity of the lure through the water.
This is achieved by providing the lure with a first member, a second member positioned rearwardly of the first member, means for producing relative rotational movement between the members at a angular velocity substantially directly proportional to the forward velocity of the lure through the water, the members having means for generating sonic waves of a frequency substantially directly proportional to their relative angular velocity. Along with this, a simultaneous control of overtones can be effected. The combination of single frequency control and overtone control affords better simulation of natural insect sounds and is a more effective fishing lure.
This invention also relates to lures which, rather than providing single frequency musical notes, are constructed to produce a simultaneous combination of musical notes, preferably a triad in either the major or minor scale. This is achieved by providing a lure which while moving through the water at any given velocity has a first means for generating sonic waves of one frequency, second means for generating sonic waves of a second frequency and third means for generating sonic waves of a third frequency, these frequencies together forming a musical triad. Fish are attracted by the enticing sounds and trail the lure closely, eventually investigating it for its edible qualities with the inevitable result of another happy fisherman.
In another respect, the invention involves the specific preferred construction of a lure which has attachment means connectible by a fishing line so that movement of the fishing line will draw the lure forwardly in the water. A rotary member such as a propeller is supported for rotational movement about the longitudinal axis of the device and has blades with surfaces lying at acute angles to the longitudinal axis. A second member which lies adjacent to the rotary member is provided with obstructions which lie in the path of water moving between the blades, these obstructions being discontinuous in directions circumferential to the longitudinal axis, thereby presenting a varying impediment to water flowing between the blades to generate sonic waves in the water.